The present invention relates to a new and improved construction of a sliding shoe or member for pusher or continuous heating furnaces, which serves for the sliding transport through the furnace of heated objects which are placed upon the sliding shoe. The sliding shoe has an at least approximately U-shaped profile or cross-sectional shape and is provided with downwardly protruding legs serving for the laterally guided support of the sliding shoe on the rail or rail means of the pusher-type furnace.
For the heat or thermal treatment of bars or the like which are formed of aluminium or aluminium alloys and possessing a weight of several tons there are used so-called pusher-type or continuous heating furnaces. The bars are advanced through these furnaces and exposed to annealing temperatures of several hundred degrees centrigrade.
For the bar through-passage or feed through the furnace the bars or other treated stock are placed upon sliding shoes or elements which are displaceable upon rail means provided in the furnace. As a rule, such displacement is performed by a hydraulic pusher or feeding device which can develop a drive or motive power of several hundred tons.
If the furnace length and thus the displacement path of the therefore heavily loaded sliding shoes supported upon the rail means amounts to twenty meters and more, it will be readily appreciated that a considerable problem exists in maintaining the lubrication supply between the sliding shoes and the rail means.
This problem remains practically unsolved at a prior art furnace where the lubricant, for instance in the form of a graphite-oil mixture or the like, is applied between the sliding shoes and the rail means before the sliding shoes are placed thereupon. Even after a few meters of displacement of the sliding shoes upon the rail means such applied lubricant is consumed, whereupon the remainder of the displacement path is performed with dry sliding surfaces. The consequences of this are high wear and the need for a frequent exchange of the sliding shoes and the rail means.
Another heretofore known method involves using a dry, powdery or pulverulent graphite lubricant which is delivered to the rail means from substantially funnel-shaped storage chambers provided in a sliding shoe. Thus, while a limited lubrication can be maintained over the whole length of the displacement path, these measures are expensive and complicated.